Instead, frailty-based illness-death multi-state models [1]}, [2]} characterize the dependency of semi-competing risks and covariates, while also enabling absolute joint risk prediction across time [3]}. These methods comprise three cause-specific hazard submodels for: (i) the non-terminal event; (ii) the terminal event without the non-terminal event; and, (iii) the terminal event after the non-terminal event. Different covariates can affect each hazard differently, and the interplay of these submodels determines the overall covariate-outcome relationship. A person-specific random frailty shared across the submodels captures residual dependence between the two events.
